Steel refining material for reductive steel refining and granulation method thereof

ABSTRACT

The present invention is directed to a granulating method of steel refining material for reductive steel refining, comprising the steps of: mixing at least steelmaking dust, aluminum ash and a resin component of a toner binder so as to form a mixture; and compressing and granulating the mixture so as to obtain a granulated steel refining material, wherein the resin component comprises an additive for enhanced lubricity and flowability, and no external heating is applied in the step of mixing and the step of compressing and granulating.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a granular material for processingof steelmaking dust and its manufacturing process, where the saidmaterial is used to collect valuable metal from composite powder-typedust consisting of metal and metal oxide generated with high temperatureexhaust gas form steel-making apparatus such as electric furnace andconverter, and wastes such as scale collected from annealing processesbefore and after steel milling or acid cleaning process (so calledsteelmaking dust), also the material aforementioned is made fromaluminum ash molded and solidified with binder which is a resin materialsuch as electrophotographic developer either sub-standard toner from itsmanufacturing process or those collected from the market for recycling,thus the material has high grain strength and high reduction efficiency.

2. Description of the Related Art

There are various methods to reuse toner. In Japanese Patent ApplicationLaid-Open (JP-A) No. 2001-003063, following topics are discussed; a)judging from toner component and property, setting objectives as beingable to utilize the toner which is ultra-fine grain and easy to disperseand to provide an easy handling waste toner processing method, b)finding that 70-80% of toner in the market includes 40% by weight to 50%by weight of iron powder also the particle size of the toner is severalmicro meters up to 20 μm, c) it is conclude that to utilize the wastetoner at iron mills, to be more specific, to mix the waste toner withthe materials for sintering by a mixing apparatus then the mixture issintered by the sintering apparatus, where the iron powder included inthe waste toner is used as iron source and a part of resin included inthe waste toner is burnt to heat as a substitute of powder coke, and thewaste toner does not disperse because it is sintered by getting mixedwith other raw materials for sintering for easier handling.

Also in JP-A No. 2003-138320, it is stated that conventional binder hasseveral drawbacks such as needing water to granulate, difficult tomaintain the form and generating a large volume of black fume todeteriorate the environment thus a binder is proposed to improve thedrawbacks abovementioned which includes a resin having a suitablesoftening temperature as binding resin for toner, preferably 100° C. orlower, such as polyol resin, styrene-acrylic copolymer or polyesterresin. Also it is described that the waste toner can be used for thebinder as described above and it is advantageous to manufacture a fluxfor steel-making based on aluminum waste such as aluminum dross as wellas aluminum ash because these do not need water and these arewater-resistant.

In case of JP-A No. 2003-251323, a recycle system is proposed which isintended to provide an apparatus having efficient parallel processingcapability of multiple recycling jobs. The system includes communicationunit which receives input information regarding with subject ofrecycling and has CPU, RAM and ROM to send first sorting condition tosort the subject materials for recycling by disintegration condition,second sorting condition by raw material and third sorting condition byrequired following steps later to sort the subject materials to eachcorresponding steps to achieve the purpose of the invention.

However, the technology described in the JP-A No. 2001-003063aforementioned defines that the recycling process is provided by inverseonerous contract (the toner supplier pays). Because, based on the aboveproposal, the resin (binder resin) as a major component of the tonerdoes not provide enough added value. Though the resin included in thetoner can be used to substitute coke, it is only a part and the majorityis still exhausted as waste gas and treated by waste gas treatmentapparatus in the steel-making process. Also, concentration of addedtoner at the sintering process is limited to 0.5% or lower because tonercomposition varies by the type of toners and the variation could affectreduction status of sintered minerals. Thus the toner is regarded ashaving low functional efficiency (therefore economically valueless) forsintering material.

Though the technology described in JP-A No. 2003-138320 mentioned beforerealizes a recycling of valuable material, it is limited to the tonerwhich does not include iron (non-magnetic toner) as subject ofrecycling. Therefore, the process shown in JP-A No. 2001-003063aforementioned has to be applied for magnetic toner.

On the other hand, it has historically been known that metal aluminumand carbonaceous reducer (organic carbonaceous material) are used toreduce the steelmaking dust to collect valuable metallic materials.

Recycling of the steelmaking dust has been tried in a various ways inthe past. For example, a method to dry and crush the steelmaking dustand process it in a electric furnace using arc, also a method to put thedust in a furnace with reducing agents such as coke to reduce andcollect metal oxide are proposed (Japanese Patent ApplicationPublication (JP-B) No. 64-005233, JP-A No. 8-337827). However, theseconventional methods require additional reducing agents thus the costfor recycling of the steelmaking dust exceeds the merit of recycling.Another proposal (JP-B No. 3146066, JP-A No. 11-302749) is made toefficiently collect valuable metals in the steelmaking dust though, theproposal has a problem since it needs vertical melting reducing furnace,a rather unique type, and the user has to have the furnace.

Though the recycling of the steelmaking dust as a resource with reducingagents such as coke in an electric furnace has been known, the reductionefficiency is low and material's powder shape inevitably makes workingenvironment deteriorated at collection, transportation and input intothe furnace. To avoid these problems as mentioned above, a proposal hasbeen made to add water, starch or PVA as binder to granulate. However,such method only provides the grain having low grain strength aftermolding and it necessarily generates dust at transportation to thefurnace and at pouring into the furnace making low collection efficiencyand deterioration of work environment unavoidable. Though othergranulating methods of steelmaking dust with higher grain strength areproposed (JP-A No. 2001-214222, JP-A No. 2001-294947), the methodsrequire limited selection of binders to increases the cost and in caseof utilizing waste plastic materials as binder, problems are generatedthat plastic contents might be higher and it affect the variation offinal products also it limits granulation machine and grainconfiguration. Also, sub-standard portion from manufacturing plant ofelectrophotographic developer (such as toner) and electrophotographicdeveloper collected from the market with copiers and printers mainly forrecycling purpose are utilized as carbon source for blast furnace butthese have a problem of being treated by inverse onerous contract.

The inventor of the present invention has already proposed a tonerrecycling system which consists of toner collection process for usedtoner and sub-standard toner among those produced in a plant up to apredetermined extent, and a granulating process where the tonercollected as above is used as raw material and added with aluminum ashfrom aluminum refining process (JP-A No. 2002-196487).

OBJECTS AND ADVANTAGES

The present invention aims for solving problems discussed above.

An object of the present invention is to improve a collection efficiencyof valuable metal to enhance merit of collection, by using compositedust including metal and metal oxide collected from steel makingfacility such as electric furnace or converter with high temperatureexhaust gas, and waste including Fe such as scale collected fromannealing and acid wash processes before and after steel milling process(hereinafter, those dust and waste are called as “steelmaking dust”)together with aluminum ash. Such steelmaking dust is mixed with aluminumash so as to adjust basicity, thereby reduction reactivity is increasedutilizing metal aluminium within the aluminium ash.

Another object of the present invention is to further enhance reductioncapability and enable to recycle metal iron content of magnetic toner asiron resource, by mixing a developer for electrophotography with thesteelmaking dust and aluminium ash, in which the mixture is softened orliquidized by heat applied at granulation, then the developer can beused as a binder to bind the powder materials of the mixture.

Yet another object of the present invention is to form a granulatedrefining material having high molding strength without deteriorationunder working environment, to efficiently collect valuable metals fromsteelmaking dust and the developer for electrophotography, and toincrease resource recycling efficiency of waste developer.

SUMMARY OF THE INVENTION

To resolve above issues, the inventors of the present invention madeserious studies to reach the present invention by finding out; a) metalcomponent within steelmaking dust can be efficiently collected by mixingthe steelmaking dust with aluminum ash to adjust basicity andcomposition, b) metal oxide can be reduced efficiently by metal aluminumwithin aluminum ash which has high reduction capability, c) bindingeffect is increased when toner binder resin including additives orelectrophotographic developer including toner binder resin are addedbecause of excellent flowability of these materials help even dispersionand mixture also the resin included in the electrophotographic developeris softened or molten by heat at molding thus a binding effect overpowder component is seen, d) resin and carbon provide reduction effect,and e) all electrophotographic developer including resin type as well asmagnetic type can be used. Therefore, the “additive” at presentinvention means wax component, metallic salt with higher fatty acid suchas zinc stearate, amides with higher fatty acid such as amide stearate,and fine particle of metal oxide such as alumina, titanium oxide andsilica that are added to electrophotographic toner and developer tocontain agglomerating property of toner and photo developer particles,also to increase lubrication property as well as flowability of thosematerials. These additives are sorted to types one of that is mixed withbinder resin for toner at toner manufacturing process then (internaladditive) exudates to the surface of toner particle at image-forming orfixing, and the other that is external additive added to toner ordeveloping solution later (fine particles of alumina and fine particlesof titanium are often sorted as this type). Waxes could existsimultaneously as internal additive and external additive in a sametoner or developing solution. The ratio of those additive compared to100 parts by weight of binder resin is preferably 0.01 parts by weightto 40 parts by weight, and 0.1 parts by weight to 30 parts by weight ismore desirable.

The first aspect of the present invention is a granulating method ofsteel refining material for reductive steel refining, comprising thesteps of: mixing at least steelmaking dust, aluminum ash and a resincomponent of a toner binder so as to form a mixture; and compressing andgranulating the mixture so as to obtain a granulated steel refiningmaterial, wherein the resin component comprises an additive for enhancedlubricity and flowability, and no external heating is applied in thestep of mixing and the step of compressing and granulating.

The second aspect of the present invention is a granulating method ofsteel refining material according to the first aspect, wherein the steelrefining material is charged into electric furnace or ladle furnace soas to collect metal and metal oxide from the steelmaking dust.

The third aspect of the present invention is a granulating method ofsteel refining material according to the first aspect, wherein the stepof mixing comprises a step of kneading the steelmaking dust, thealuminum ash and the resin component.

The fourth aspect of the present invention is a granulating method ofsteel refining material according to the third aspect, wherein the stepof kneading and the step of compressing and granulating generate heat,the heat generated in either step allows the resin component to bind themixture.

The fifth aspect of the present invention is a granulating method ofsteel refining material according to the first aspect, wherein the resincomponent is obtainable from a developer for electrophotography, and thestep of mixing is a step of mixing the steelmaking dust, the aluminumash and the developer containing the resin component.

The sixth aspect of the present invention is a granulating method ofsteel refining material according to the fifth aspect, wherein thedeveloper is an off-specification product obtained in a process ofdeveloper manufacturing, or a recycled developer.

The seventh aspect of the present invention is a granulating method ofsteel refining material according to the first aspect, wherein heatingat 50° C. to 200° C. is applied in a subsequent step of the compressingand granulating, so as to impart high crush strength and low powdercontent to the granulated steel refining material.

The eighth aspect of the present invention is a granulating method ofsteel refining material according to the first aspect, wherein thecompressing is carried out by using a high pressure molder in the stepof compressing and granulating.

The ninth aspect of the present invention is a refining material forreductive refining of steel, which comprises: steelmaking dust, aluminumash and a resin component of a toner binder wherein the resin componentcomprises an additive for enhanced lubricity and flowability.

The tenth aspect of the present invention is a refining materialaccording to the ninth aspect, wherein the resin component is obtainablefrom a developer for electrophotography, and the refining materialcomprises the steelmaking dust, the aluminum ash and the developercontaining the resin component.

The eleventh aspect of the present invention is a refining materialaccording to the tenth aspect, wherein the developer is anodd-specification product obtainable in a process of developermanufacturing, or a recycled developer.

The twelfth aspect of the present invention is a refining materialaccording to the tenth aspect, wherein the content of steelmaking dustis from 30% by weight to 80% by weight, the content of aluminum ahs isfrom 10% by weight to 50% by weight, and the content of developer isfrom 2% by weight to 20% by weight.

The thirteenth aspect of the present invention is a refining materialaccording to the ninth aspect, wherein the content of additive is from0.01 parts by weight to 40 parts by weight relative to 100 parts byweight of the resin component.

The fourteenth aspect of the present invention is a refining materialaccording to the ninth aspect, wherein the additive is at least one ofmetal oxide, salt of higher fatty acid, higher fatty acid amide, andwax.

The fifteenth aspect of the present invention is a refining materialaccording to the fourteenth aspect, wherein the additive comprises zincstearate.

The sixteenth aspect of the present invention is a refining materialaccording to the ninth aspect, wherein the steelmaking dust containsmetal and metal oxide, the metal and metal oxide are collectable bycharging the refining material into electric furnace or ladle furnace.

The seventeenth aspect of the present invention is a refining materialaccording to the ninth aspect, wherein the refining material isobtainable from the process comprising the steps of mixing at least thesteelmaking dust, the aluminum ash and the resin component so as to forma mixture; and compressing and granulating the mixture so as to obtainthe granulated steel refining material, wherein no external heating isapplied in the step of mixing and the step of compressing andgranulating.

The eighteenth aspect of the present invention is a refining materialaccording to the seventeenth aspect, wherein the step of mixingcomprises a step of kneading the steelmaking dust, the aluminum ash andthe resin component.

The nineteenth aspect of the present invention is a refining materialaccording to the eighteenth aspect, wherein the step of kneading and thestep of compressing and granulating generate heat, the heat generated ineither step allows the resin component to bind the mixture.

The twentieth aspect of the present invention is a refining materialaccording to the seventeenth aspect, wherein heating at 50° C. to 200°C. is applied in a subsequent step of the compressing and granulating.

The present invention mixes steelmaking dust collected from steel makingprocesses and steel milling processes with aluminum ash and a developerfor electrophotography, adjusts basicity or composition of the mixture,applies compression molding heat or heating, and granulates. By chargingthe grain into electric furnace or ladle furnace, a reduction capabilityis enhanced as a result of binding effect, carbon content, and resincomponent content of the developer for electrophotography, as well asallowing an iron content thereof to recycle as iron resource.

In the present invention, it is preferable to use a developer forelectrophotography containing a large amount of binder resin, such as aresinous toner, in view of binding effect. It is also preferable to usea developer for electrophotography containing magnetic ferrite in viewof collection of valuable metal for recycling steelmaking dust. At thecurrent situation, majority of the developer containing magnetic ferriteis not used as recourse, thus utilization of such developer ispreferable in view of environmental protection and recycling.

The developers related to the present invention are powder and usuallyinclude wax as an external additive so as to have high flowability atnormal temperature and to easily mix with other components. Also aluminais included to adjust its basicity and to inhibit the increase ofmelting point. CaO, a typical agent to eliminate sulfur component has ahigh melting point as 2750° C., is not required only to maintain highbasicity for efficient desulfurization though, a volume application ofCaO is necessary to maintain flowabilty of slugg corresponding to SiO₂content as much as CaO/SiO₂=2.5 mol to 3.0 mol. Therefore,resulfurization is prevented at reduction step where mainly sulfur andoxygen are eliminated, steel running-off step and off-furnace refiningstep (a step following an oxidization step which eliminate Si (includingresidual metal Si for deoxidization in the molten steel), P and C, wheremainly S and O are eliminated from molten steel). Also, reflecting therecent toner resin characteristics of low melting point and quicksettlement responding to the requirement for energy saving and quickfunction for electrophotographic devices, it can be mixed with aluminumash and steelmaking dust evenly, and by mixing made of mechanical forceat agitation and mixing or pressurized molding to make granulating(briquette making) easy, also with high mechanical strength after cooleddown and solidified, it provides a high strength grain for refining. Inaddition, the refining process of steelmaking dust is generallydelegated to Zinc collection contractor with a payment of process fee.Since the zinc content of the present invention is higher than that ofsteelmaking dust, the process fee is expected to be discount inproportion of the amount of the collected zinc. The zinc content of thesteelmaking dust is generally estimated as 15% to 20%, but the zinccontent of the present invention is increased by zinc obtainable fromthe zinc stearate within the developer.

By using resin which flowability is enhanced with external additive asbinder, high mold strength grain with high reduction efficiency isprovided and it means the grain made from steelmaking dust characterizedby an efficient recycling of valuable metal with improved reduction ofmetal and metal oxide within the steelmaking dust. Since this processutilizes materials of sub-standard portion from manufacturing processand recycled ones from market, it is very advantageous for environmentas well as economy.

As aluminum ash mainly consists of metal aluminum and alumina, by usingthose from waste aluminum of aluminum melting steps such as aluminumrefining process and aluminum molding process, or using wastes which isnot effectively collected as molten aluminum because of configuration orsurface area, it is very advantageous for environment as well aseconomy.

A high reduction capacity and high granulating mold strength grain,which is characterized by using a mixture of steelmaking dust andaluminum ash with adjusted contents as major raw material, withelectrophotographic developer as an additive for binding purpose to beused to collect metal and metal oxide included in the steelmaking dust,is obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The mixed particle of metal and metal oxide used as steelmaking dust inthe present invention is generated and collected in the processes ofelectric furnace and other steel making processes, and scales (Fe andsmall amount of Fe suboxide) used are collected from acid cleaning andannealing steps before and after milling process. In case of using dustcollected by wet scrubber or scales generated and collected at cleaningprocess, those may contain a lot of water thus it is preferable toeliminate water to a certain extent.

The steelmaking dust used in the present invention can provide valuablemetal recycling from ordinary steel, but the stainless steelmaking dustis more economically effective because it can recycle higher valuemetals such as Ni and Cr.

The “developer for electrophotography” stated in the present inventionincludes materials such as lycopodium particle, two-part developercomprising colored resin powder and glass beads, one-part non-magneticinsulating atomized particle, one-part non-magnetic insulating toner,two-part developer comprising electroscopic powder (toner) and magneticcarrier (diameter: 50 μm to 700 μm), conductive toner, partiallyconductive magnetic-toner, two-part developer comprising toner andbinder carrier, insulating magnetic-toner, two-part developer comprisinginsulating magnetic-toner and conductive magnetic-powder (magneticcarrier), magnetic-toner consisting of 2 different type of toners thatdiffers in particle size and frictional electrical resistance, and thoseare added with additives for enhanced lubricity and flowability. Theadditives include metal oxide such as alumina, titanium oxide andsilica, metallic salt of higher fatty acid such as zinc stearate, higherfatty acid amide such as stearic acid amide, wax, and the like.

As abovementioned, the developer used in the present invention is powdermaterial which has high flowability at normal temperature and easy tomix with other materials, and the basicity thereof is adjusted and themelting point of the refining material is so maintained as not toincrease. Therefore, resulfurization at reduction step where mainly Sand O are eliminated, steel output step and off-furnace refining step (astep mainly eliminate S and O from molten steel) is prevented. Inaddition, the developer is easily fused and has a low viscosity atmelted state, reflecting recent toner resin characteristic such as lowtemperature and quick fixation, thus the developer is evenly mixed withaluminum ash and steelmaking dust, melt-kneaded with an application ofmechanical force through stirring, compression molding and the like,thereby easily being granulated (forming briquette). The thus obtainedgranulated refining material has high strength. The steelmaking dust isexpected to show a lower processing cost because its zinc content isincreased by that from zinc stearate. It is possible to judge whether arefining material is based on the present invention or not by seeingproperty of binder resin, property of external additive and size ofcolorant particle. Ordinary MP (melting point) of the resin for tonerbinder is, from viewpoints of fixing and heat resistant capability as atoner image recording medium over high quality paper, 180° C. or lessthan that, preferably 140° C. or less. Additives used are, asaforementioned, metal oxide such as alumina, titanium oxide and silica,metallic salt of higher fatty acid such as zinc stearate, higher fattyacid amide such as stearic acid amide, and wax. Since the averageparticle size of toner is usually 4 μm to 10 μm, a particle size ofcolorant included in the toner is naturally less than that of the toner,which is much smaller than a particle size of ordinary colorant.

By using the resin with enhanced flowability by additives as a binder,the granulated material with high reduction efficiency and high moldingstrength is obtained. The granulated material refining from thesteelmaking dust works for efficient recycling of metal and metal oxidecontained in the dust. It also utilizes, as a developer,off-specification product obtained in a process of developermanufacturing, or a recycled developer collected from market, it is veryadvantageous for environment and economy.

As aluminum ash mainly consisting of metal aluminum and alumina, it ismade from wastes collected from aluminum refining and casting processes,or wasted portion of molten aluminum which is difficult for recyclingdue to configuration or surface area, thus it is very advantageous forenvironment and economy.

A granulated material refined from steelmaking dust, characterized byrecycling of metal and metal oxide as valuable metal, is obtained byusing a mixture of the steelmaking dust and the aluminum ash as majorcomponent also added with the developer for electrophotography asbinder, to have high reduction efficiency and high mold strength.

Hereinafter, the present invention is more specifically described.

At preparation of raw materials, the water content of the steelmakingdust is adjusted to 10% by weight or less by means of natural seasoning,or a dryer such as rotary kiln, tunnel furnace or electric furnace.

Using mixer or suitable means, 30% by weight to 80% by weight of thesteelmaking dust, 10% by weight to 50% by weight of the aluminum ash,and 2% by weight to 20% by weight of the developer forelectrophotography are thoroughly mixed. In the case that thesteelmaking dust and the aluminum ash for use require an adjustment ofproperties thereof, aluminium based additives may be add, and the addedamount thereof is suitably adjusted depending on compositions orparticle sizes of the steelmaking dust, aluminum ash and developer. Thedeveloper may be used singly or in combination of two or more.

Then the mixture described above is compressed granulated to form agranulated refining material. A high pressure molder which generatesenough heat is desirable for this forming step though, machinesgenerating low heat such as low pressure molder or pelletizer might workas well. When heat at 50° C. to 200° C. is applied to the material aftercompressing and granulating, the granulated refining material attainshigher crush strength and lower powdering rate, thereby the granulatedrefining material is able to be reused as a material for electricfurnace.

Since the granulated refining material from steelmaking dust uses thedeveloper for electrophotography as binder, it is a fine particle withhigh flowablity to make a good dispersion over whole raw materials evenwith a small amount of addition. Thus it makes the granulated refiningmaterial having a high hardness and low powdering rate also makes it avery safe binder without potential fire, contrary to using HARTALL whichcould start fire by heat.

Since the major components of the developer are organic materials, thoseare burnt off at electric furnace, ladle furnace or converter thus noissue to increase steelmaking dust and it is an effective additive asreduction agent and heat generator.

As aforementioned, the present invention uses the steelmaking dust, thealuminum ash and the developer for electrophotography to make thegranulated refining material to make the components of the dustrecyclable as resources of Fe, Ni or Cr sources thus it can reduce steelmaking cost and is very advantageous for economy.

Though there are many plastic wastes used as binders, it is necessary tomake them fine particle to show binding effect with small volume usage.Therefore, ordinary plastics, requiring complicated processes to make afine particle because of increasing viscosity affected by the heatgenerated, costs a lot and is not suitable for granulating ofsteelmaking dust from cost evaluation viewpoint.

Though the present invention is more specifically explained referring tothe embodiments hereinafter, it is not limited to those embodiments.

Embodiment 1

The property of binder and binding effect were observed by forming agranulated refining material using a developer for electrophotography,i.e., two-part resinous toner and one-part magnetic toner as well as aplastic material which is also used as binder for fuel or reductionagent.

Ordinary waste plastic materials are, for example, plastic bottle, bag,packaging material, film, tray, cup, magnetic card, magnetic tape,fleconbag, board, coated wire, household electrical goods, office supplyand automobile part. Several of these were crushed and mixed bydual-axis low speed cutter (made by FUJI SEIKI Co. Ltd, Model:FC-22/100) to make an intermediate batch of materials then it wasprocessed by fine crushing high speed cutter (SUPER ALLOY CUTTING, madeby Tai Chong Enterprise Co. Ltd, Model: K.G/CY 001) (however, in case ofmicro crushing test, a stamp mill for micro crushing (made by CMT Co.Ltd, VIBRATING SAMPLE MILL, Model: Ti-100) is used) to make the crushedmixture of plastic materials capable of being mixed within steelmakingdust, then sorted by circular vibration sieving machine (made by KOWAKOGYO KK, Model: KGO-1000) to make the size of whole particles gothrough mesh 100 (150 μm or less).

Steelmaking dust, aluminum ash, and each of two-part resinous toner,one-part magnetic toner and plastic powder were mixed with contentsshown in Table 1. 100 kg of the mixture were mixed by V-type mixer (madeby SANEI KK, Model: OV-II-130), mortar mixer (made by TOKAI MachineryKK, Model: Mini3) and a mixer (made by SHINKO FLEX KK, a modifiedmixer/tester having vanes within a drum and drum itself rotates) for 15minutes, then the mixture was granulated by SHINTOKOGYO BriquetteMachine (made by SHINTOKOGYO Ltd, Model: BCS-25) and the moldingstrength (crush strength) of the granulated material at a predeterminedtemperature was measured by crush tester (made by STRICT OBSERVANCEIMADA, Model: DPSHII-R).

The result of crush strength test is shown in Table 2. In case of thedeveloper, crush strength was increased proportionally to amount ofadditives and heating temperature though, the crush strength of plasticpowder was lower than those of the developer and crush strength was notproportional to added amount. The numbers shown in Table 2 are averagevalues and the range of 10 data point per sample of the developer waswithin 20% though, the variation in case of plastic powder exceeded 50%in some samples thus apparently there was a poor dispersion. This isbecause that external additives are used for the developer to improveflowability and it helps the granulated material increase dispersivenessand even small addition can be distributed well over whole material toshow necessary property for a binder, whereas plastic powder has poordispersiveness and larger amount of addition could provide moreregulated binding effect and less peaky total strength but compositionof product is not satisfactory. TABLE 1 MATERIAL CONTENT (% BY WEIGHT)PLAS- SAM- ALUMI- TWO- ONE- TIC PLE STEEL NUM COMPONENT COMPONENT POW-NO. DUST ASH TONER TONER DER 1 57 40 3 — — 2 55 40 5 — — 3 52 40 8 — — 450 40 10  — — 5 57 40 — 3 — 6 55 40 — 5 — 7 52 40 — 8 — 8 50 40 — 10  —9 57 40 — — 3 10 55 40 — — 5 11 52 40 — — 8 12 50 40 — — 10 

TABLE 2 CRUSH STRENGTH (kg/mm²) SAMPLE TEMPERATURE ° C.) NO. A.T. 40 6080 100 120 150 200 250 1 50.7 53.6 60.4 66.8 70.2 78.0 90.8 105.9 70.3 260.3 74.1 81.2 86.9 95.7 130.8 172.3 198.0 107.7 3 78.3 115.2 134.5156.8 182.9 199.0 >200 >200 142.1 4 98.5 142.3177.7 >200 >200 >200 >200 >200 189.1 5 39.8 45.3 52.9 61.1 65.4 71.681.1 97.5 68.9 6 45.6 57.8 66.7 70.3 81.3 100.3 150.3 177.6 99.5 7 55.871.1 88.6 110.5 160.5 188.0 196.9 >200 128.3 8 70.6 95.3 108.2152.7 >200 >200 >200 >200 157.2 9 9.0 8.7 11.8 20.4 18.6 25.6 25.4 25.825.9 10 11.3 12.3 15.9 30.1 25.6 30.4 28.9 35.9 31.8 11 19.1 15.4 20.635.6 35.9 39.4 37.4 36.1 40.6 12 15.4 15.1 20.2 40.9 35.8 38.4 50.2 42.648.3

Judging from the results shown in Table 2, it is understood thatdeveloper as a binder for powdery raw materials does not needpre-treatment and it has necessary property for a binder.

Also, it was confirmed that by utilizing the heat generated atcompressing and granulating or application of heat of 200° C. or lessafter compressing and granulating, the crush strength was increasedfurther and binding effect was enhanced with this material.

Embodiment 2

As an example to demonstrate the binding effect at mass-productionapparatus, 3,600 kg of steelmaking dust, 2,100 kg of aluminum ash(including 25% by weight to 35% by weight of metal aluminum) and 300 kgof two-part resinous toner were mixed by a mixer type apparatus made bySHINKO FLEX KK (a mixer built into mixing/molding line) for 30 minutes,then granulated by a dry and high pressure type briquette machine madein China (simulated volume production granulator, Model: LYQ3.0,production capacity on the brochure 3,000 kg/hour). The granulatedmaterial were sampled 10 pieces every 30 min from the beginning ofproduction for crush strength measurement to see variation in time. Alsocrush strength repeatability after heating was confirmed by heatingsamples at 100° C. The results of measurement are shown in Table 3. InTable 3, “time” denotes a sampling time elapsed from the start ofproduction, “volume” denotes produced volume at sampling, “crushstrength” denotes crush strength obtained by 10 sample average, and“crush strength after heating” denotes crush strength after heating at100° C. obtained by 10 sample average. TABLE 3 CRUSH STRENGTH CRUSHAFTER SAMPLE STRENGTH HEATING NO. TIME(min) VOLUME(kg) (kg/mm²) (kg/mm²)1 0.0  50-100 71.6 115.6 2 0.5 550-650 71.9 115.8 3 1.0 1150-1250 71.3115.2 4 1.5 1750-1850 71.5 115.9 5 2.0 2350-2450 71.9 116.0 6 2.52950-3050 72.1 115.5 7 3.0 3550-3650 71.8 115.7 8 3.5 4150-4250 71.3115.4 9 4.0 4750-4850 71.8 115.1 10 4.5 5350-5450 72.0 115.3 11 5.04950-6000 71.5 115.9

It was confirmed from the results shown in Table 3 that the developer asbinder showed good dispersiveness since there was no variation of crushstrength over time even if the developer was added by 5% by weight.

Then the same material was granulated by 200 kg test machine and itsmold strength was measured to see the effect of molding temperature overmolding strength. The result was shown in Table 4. In Table 4, “crushstrength” denotes crush strength just after granulating obtained by 10sample average, and “crush strength after heating” denotes crushstrength after heating at 100° C. obtained by 10 sample average.

Mold temperature of volume production machine was 70° C. and graintemperature right after granulating was 50° C., and average strengthright after granulation was 71.7 kg/mm².

Mold temperature of test machine was 50° C. and grain temperature rightafter granulating was 35° C., and average strength right aftergranulation was 45.4 kg/mm².

Crush strength of samples for post heat test from both volume productionmachine and test machine was 115 kg/mm² or more after heated at 100° C.

From above results, it was concluded that a higher crush strength graincould be manufactured by utilizing of heat generated during molding, andby adding a step of heating at 200° C. or less after compressing andgranulating, a higher molding strength grain could be manufactured.TABLE 4 CRUSH STRENGTH CRUSH STRENGTH AFTER HEATING 45.4 kg/mm² 115.8kg/mm²

Embodiment 3

Here, an embodiment of collection of valuable metals out of steelmakingdust is explained.

Major components of the steelmaking dust and aluminum ash subject tothis embodiment are shown in Table 5.

The aspect of collection yield test is as shown below.

[Furnace; (1) Electric Furnace, (2) Ladle Furnace]

[Test Operation]

(1) Electric Furnace:

[Charging Method]

Charged with Scrap into the Electric Furnace

[Evaluation Method]

Yield was calculated from molten metal contents since yields of Ni andCr charged at test were fixed.

(2) Ladle Furnace

[Charging Method]

Use Material Chatted into the Ladle Furnace

[Evaluation Method]

Yield was calculated by comparison of molten steel contents when it wasas output from an electric furnace and after being added with refiningmaterial made of steelmaking dust.

Blending ratio tested was; 60% by weight of steelmaking dust, 35% byweight of aluminum ash and 5% by weight of two-part resinous toner. Thesteelmaking dust was collected from manufacturing process of 18-8stainless steel (Cr: 17-19%, Ni: 8-10%) and the material was as shown inembodiment 2 granulated by mass-production apparatus.

The major contents of the blended material are shown in Table 6. TABLE 5MATER- CONTENTS OF RAW MATERIAL (W/%) IAL T—Fe T—Cr T—C T—Ni M—Al Al₂O₃SiO₂ STEEL- 48.7 7.9 7.5 4.5 — — — MAKING DUST ALUM- 0.8 — 2.6 — 33.042.0 8.0 INUM ASH

TABLE 6 MATER- CONTENTS OF BRIQUETTE (W/%) IAL T—Fe T—Cr T—C T—Ni M—AlAl₂O₃ SiO₂ BLEND- 29.2 4.8 8.6 2.5 11.6 14.7 2.8 ED BRI- QUETTE

Result of collection rate in molten steel when blended briquette wascharged into ladle furnace is shown in Table 7.

As reference of valuable metal collection, result of collection ratewhen briquette with only steelmaking dust was added is also shown.

Among test results shown there, when the collection rates of valuablemetals for steelmaking dust alone sample and aluminum ash blended sampleare compared, apparently the sample, which includes aluminum ash andelectrophotographic developer for binder effect and as reduction agent,shows higher rate. In case of steelmaking dust alone, it needs basicityadjusting agent for slag to efficiently collect valuable metals, alsoreductive components such as M—Al or C because the steelmaking dustinclude a lot of metal oxide. Since generally reduction efficiency isimproved when the reduction agent is dispersed to whole material andcollection rate is increased, using electrophotographic developer withexternal additive to enhance flowability increases reduction capability.

Other powder such as those collected from machining process usingstainless cut wire as projectile can also be used to be blended toproduce granulated refining material from steelmaking dust for valuablemetal recycling. Also addition of Ni sludge is effective. TABLE 7COLLECTION RATE OF VALUABLE METAL (%) SAMPLE Fe Cr Ni MIXED 93 90 92BRIQUETTE STEELMAKING 35 20 33 DUST

1. A granulating method of steel refining material for reductive steelrefining, comprising the steps of: mixing at least steelmaking dust,aluminum ash and a resin component of a toner binder so as to form amixture; and compressing and granulating the mixture so as to obtain agranulated steel refining material, wherein the resin componentcomprises an additive for enhanced lubricity and flowability, and noexternal heating is applied in the step of mixing and the step ofcompressing and granulating.
 2. A granulating method of steel refiningmaterial according to claim 1, wherein the steel refining material ischarged into electric furnace or ladle furnace so as to collect metaland metal oxide from the steelmaking dust.
 3. A granulating method ofsteel refining material according to claim 1, wherein the step of mixingcomprises a step of kneading the steelmaking dust, the aluminum ash andthe resin component.
 4. A granulating method of steel refining materialaccording to claim 3, wherein the step of kneading and the step ofcompressing and granulating generate heat, the heat generated in eitherstep allows the resin component to bind the mixture.
 5. A granulatingmethod of steel refining material according to claim 1, wherein theresin component is obtainable from a developer for electrophotography,and the step of mixing is a step of mixing the steelmaking dust, thealuminium ash and the developer containing the resin component.
 6. Agranulating method of steel refining material according to claim 5,wherein the developer is an off-specification product obtained in aprocess of developer manufacturing, or a recycled developer.
 7. Agranulating method of steel refining material according to claim 1,wherein heating at 50° C. to 200° C. is applied in a subsequent step ofthe compressing and granulating, so as to impart high crush strength andlow powder content to the granulated steel refining material.
 8. Agranulating method of steel refining material according to claim 1,wherein the compressing is carried out by using a high pressure molderin the step of compressing and granulating.
 9. A refining material forreductive refining of steel, comprising: steelmaking dust; aluminum ash;and a resin component of a toner binder wherein the resin componentcomprises an additive for enhanced lubricity and flowability.
 10. Arefining material according to claim 9, wherein the resin component isobtainable from a developer for electrophotography, and the refiningmaterial comprises the steelmaking dust, the aluminum ash and thedeveloper containing the resin component.
 11. A refining materialaccording to claim 10, wherein the developer is an off-specificationproduct obtainable in a process of developer manufacturing, or arecycled developer.
 12. A refining material according to claim 10,wherein the content of steelmaking dust is from 30% by weight to 80% byweight, the content of aluminum ash is from 10% by weight to 50% byweight, and the content of developer is from 2% by weight to 20% byweight.
 13. A refining material according to claim 9, wherein thecontent of additive is from 0.01 parts by weight to 40 parts by weightrelative to 100 parts by weight of the resin component.
 14. A refiningmaterial according to claim 9, wherein the additive is at least one ofmetal oxide, metal salt of higher fatty acid, higher fatty acid amide,and wax.
 15. A refining material according to claim 14, wherein theadditive comprises zinc stearate.
 16. A refining material according toclaim 9, wherein the steelmalking dust contains metal and metal oxide,the metal and metal oxide are collectable by charging the refiningmaterial into electric furnace or ladle furnace.
 17. A refining materialaccording to claim 9, wherein the refining material is obtainable fromthe process comprising the steps of: mixing at least the steelmakingdust, the aluminum ash and the resin component so as to form a mixture;and compressing and granulating the mixture so as to obtain thegranulated steel refining material, wherein no external heating isapplied in the step of mixing and the step of compressing andgranulating.
 18. A refining material according to claim 17, wherein thestep of mixing comprises a step of kneading the steelmaking dust, thealuminum ash and the resin component.
 19. A refining material accordingto claim 18, wherein the step of kneading and the step of compressingand granulating generate heat, the heat generated in either step allowsthe resin component to bind the mixture.
 20. A refining materialaccording to claim 17, wherein heating at 50° C. to 200° C. is appliedin a subsequent step of the compressing and granulating.